1. Field of the Invention
A throttle valve control unit according to the invention relates to a unit to control the opening/closing of a throttle valve in a vehicle.
2. Description of the Prior Art
Among the drawings of the conventional throttle valve control unit according to the embodiment, FIG. 5 is a sectional view of an essential part of the conventional throttle valve control unit, and FIG. 6 is a plan view of a casing for the conventional throttle valve control unit.
A throttle valve tube 31 made of a metal has a tubular shape and lets an air-fuel mixture pass therethrough.
A throttle valve 32 made of a metal in a disc shape opens/closes the passage of the throttle valve tube 31 and is integrally formed with a throttle valve shaft 33 located across the center of the disc of the throttle valve 32.
A pair of bearings 34, 34 are buried in the tube wall 35 of the throttle valve tube 31 and support the throttle valve shaft 33 at both ends.
A connection chamber 36 adjacent to the throttle valve 32 is provided in a space in which the throttle valve shaft 33 is projected through one of the bearings 34.
Three transmission gears 37, 38, and 39 are engaged with each other, and the throttle valve shaft 33 is fixed at the center hole of the transmission gear 37 at one end of the arrangement of the three transmission gears 37, 38 and 39, so that the transmission gear rotates the throttle valve 32. The three transmission gears 37, 38, and 39 are provided in the connection chamber.
A slider 40 is made of a resilient metal material, and attached to a sidewall of the transmission gear 37 which has its center fixed at the throttle valve shaft 33.
A motor 41 is stored in a rectangular housing 41a and fixed at the tube wall 35 of the throttle valve tube 31 and has its motor terminal 41b and its motor shaft 41c projected. The motor shaft 41c of the motor 41 is fitted into the center hole of the gear 39 at the other end of the arrangement of the three transmission gears 37, 38, and 39. More specifically, the rotation of the motor 41 rotates the throttle valve shaft 33 through the three transmission gears 37, 38, and 39. The motor 41 is provided in the connection chamber 36.
A casing 42 made of insulating resin has a container shape whose outer shape is substantially elliptical. The casing 42 is attached to cover the connection chamber 36 from the outside, and covers the motor 41, the transmission gears 37, 38 and 39, and the slider 40.
A resistance substrate 43 that is insulating and in a U-shape has conductive paths 44 on the surface, and is provided at one end of the casing 42. When the casing 42 is mounted over the connection chamber 36, the conductive paths 44 of the resistance substrate 43 slide into contact with the sliders 40 attached at the sidewall of the transmission gear 37.
A sensor terminal 45 made of a metal conductor in a strip shape has one end connected to the conductive path 44 at the resistance substrate 43. The sensor terminal 45 is formed together with the casing 42 by insert molding, and therefore is buried in the insulating resin of the casing 42 except for a surface.
A motor feeding terminal 46 is a strip shaped metal conductor, one end of which is raised upward as a clip shaped motor feeding portion 46a from the bottom of the casing 42 compared to the other part of the motor feeding terminal 46. The motor feeding terminal 46 is formed together with the casing by insert molding, and therefore buried in the insulating resin of the casing except for the motor feeding portion 46a. When the casing 42 is mounted over the connection chamber 36, the motor terminal 41b and the motor feeding portion 46a are connected.
A connector housing 47 made of insulating resin has a recessed portion and is integrally formed with the casing 42. The sensor terminals 45 and the motor feeding terminals 46 gather at the connector housing 47 for connection with external connectors.
A method of manufacturing a conventional throttle valve control unit will now be described. To begin with, the casing 42 and the connector housing 47 are formed by insert-molding integrally with the sensor terminals 45 and the motor feeding terminals 46, and at the same time, the clip-shaped motor feeding portion is formed and worked. In this way, the sensor terminals 45 and the motor terminals 46 formed at the bottom of the casing 42 are gathered at the connector housing 47, so that their ends are exposed. Then, the resistance substrate 43 is attached and fixed to one end of the casing 42 so that the ends of the conductor paths 44 and the sensor terminals are connected. In a separate step, the throttle valve 32, the bearings 34, and the throttle valve shaft 33 are attached to the throttle valve tube 31, and a motor is attached in the connection chamber 36. The transmission gears 37, 38, and 39 are provided so that the gear 37 at one end of the arrangement of the gears 37, 38, and 39 has its center fixed to the throttle valve shaft 33, and the gear 39 at the other end has its center hole fixed to the motor shaft 41c. Then, the sliders 40 are attached to a side surface of the transmission gear 37 at the said one end. Finally, the assembled casing 42 is placed to cover the connection chamber, and the casing 42 is rigidly mounted to the unit assembled in the throttle valve tube in the above separate step. At the time, the clip-shaped motor feeding portion 46a on the side of casing 42 is engaged with the motor terminal 41b, while the conductive paths 44 of the resistance substrate 43 are in contact with the sliders 40 attached at the side surface of the transmission gear 37. In this way, the conventional throttle valve control unit is completed.
In the above conventional throttle valve control unit and the manufacturing method thereof, there is a connection portion to the motor terminal whose tip end is in a complicated, clip shape, and the connection portion is raised from the casing compared to the other part. The other part must therefore be distributed over the casing. The motor feeding terminal in this shape must be formed integrally with the casing by insert molding, which makes the molding die structure complicated.
It is therefore an object of the invention to provide a throttle valve control unit having a simple molding die structure and a manufacturing method thereof.
A throttle valve control unit according to the invention includes a container shaped casing, a rotation detection portion provided at the inner surface of the casing, a sensor terminal led from the rotation detection portion, exposed in a connector housing provided at the outer surface of the casing and held at the casing by insert-molding, a motor feeding terminal provided in parallel with the sensor terminal, having its one end exposed in the connector housing and held at the casing by insert molding, and its other end having an exposed part extended into the casing, and a motor feeding conductor provided separately from the motor feeding terminal and attached in the casing. One end of the motor feeding conductor is connected with the exposed part of the motor feeding terminal, and connected with a motor terminal as it is held between a pair of first folded portions provided at the other end of the motor feeding conductor. The motor feeding terminal is powered to drive a motor through the motor feeding conductor, the motor shaft of the motor rotates the throttle valve shaft to open/close the throttle valve, and the opening/closing angle of the throttle valve is detected based on the rotation transmitted to the rotation detection portion through the throttle valve shaft.
In this way, the motor feeding conductor provided separately from the motor feeding terminal is used, and this motor feeding conductor does not have to be formed integrally with the other motor feeding terminal, which simplifies the molding die structure.
One end of the motor feeding conductor is resiliently connected to the exposed portion by the second folded portion.
In this way, the connection is established only by inserting the second folded portion, in other words, the connection can simply be made.
A third folded portion is provided adjacent to the second folded portion, and the third folded portion is made into a bending portion formed between the second folded portion and an opposing wall.
In this way, the third folded portion serves as a bending portion to eliminate the effect of expansion or contraction of the casing upon the connection by the second folded portion.
The casing is provided with a pair of guide columns having a recessed portion to support the pair of first folded portions.
In this way, the first folded portion has its position surely fixed, which ensures the connection.
A method of manufacturing a throttle valve control unit according to the invention includes the steps of:
forming a sensor terminal and a motor feeding terminal at a container shaped housing by insert-molding so that the terminals each have one end exposed in a tubular connector housing and the other end exposed at the inner surface of the casing, the container shaped housing having a storing portion storing the connector housing and a resistance substrate,
storing the resistance substrate fixedly in the storing portion and connecting the resistance substrate to the other end of the sensor terminal,
mounting a slider retainer provided with a slider member in the storing portion in a rotatable manner, the slider member sliding on the resistance substrate,
fixing at the bottom of the casing a motor feeding conductor having a pair of first folded portions at one end and a second folded portion resiliently connected to the other end of the motor feeding terminal on the other end, thereby connecting the second folded portion to the other end of the motor feeding terminal,
resiliently connecting a motor terminal to the first folded portion, and
coupling a throttle valve shaft to the slider retainer.
According to the method, the motor feeding conductor separate from the motor feeding terminal is used, and therefore the molding die structure can be simplified.